Flat termo-solar collector and manufacturing process

ABSTRACT

The “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, subject of this patent, represents a radical paradigm shift, both in the manufacturing process—whose steps were minimized and subject to any degree of automation—and regarding the shape design of the solar energy gathering tubes and tightness of the metal housing that houses the collecting element. 
     The solar energy gathering tubes in accordance with this patent are manufactured with copper and have reduced costs—as the materials, shapes and manufacturing process—due to three innovative embodiments:
         1. The reducing the thickness of the copper plates to only 0.10 to 0.15 millimeters, which reduces the cost of materials and the final weight of the assembly;   2. The molding of the gathering tubes by its stamping in these thin plates, which provide structural stability to the thin plates, thereby balancing the brittleness of their low thickness with increased resistance conferred by stamping;   3. Automatic welding process through high precision and low cost laser or electrical discharge, eliminating the electrodes or manual welding, two symmetrically stamped plates, so getting through a single automatic operation a whole hermetically sealed system of tubes for water flow and solar energy gathering in a single manufacturing operation.       

     Besides this, radical costs reduction arising from the industrial design outlined above, by changing the geometry of solar collector tubes, that tend to have low internal volumes and elliptical shapes, oval, or any non-circular shape, whose largest diameters are positioned facing the sun to receive solar radiation which increase the useful area of solar energy absorption by the gathering tubes.

FIELDS OF THIS PATENT

-   Solar Heating. -   Environmental conservation through replacement of high power     production costs and environmental high burdening impact     technologies, such as hydroelectricity and fossil fuels, by solar     energy. -   Radical costs reduction of solar energy collectors manufacturing for     complying with regulations and settling needs of the lower classes.

STATE OF THE ART

The State of the Art on the production of solar energy collectors faces a serious intrinsic problem: the acquisition costs.

They are expensive.

If they are cheap they are also inefficient.

Solar collectors are expensive because they are slowly handcrafted, with intensive use of labor, which leads to high incidence of defects implying extra maintenance labor and technology disparagements associated with high initial investments.

Regarding other critical approaches, solar collectors have following advantages:

-   -   thermal energy production free of charge, environmental         conservation by avoiding hydroelectricity and fossil or nuclear         fuels consumption as well as social and environmental burdens         related to hydroelectric plant construction and grid         investments.

They are environmentally friendly even by their decommissioning because they are made from recyclable materials.

We initially introduce a brief scenario of the Brazilian situation regarding thermo-solar power gathering focusing household utilization in order to show the current technology basic parameters that will be compared later with the advances brought by this invention, viz. “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, subject of this patent.

Flat solar collectors are employed more in the residential sector. However, there is a significant interest for their exploitation in other sectors, such as public and commercial buildings, hospitals, restaurants, hotels as well as the like.

Active solar heating systems, i.e., systems that make use of solar thermal energy, involve the use of flat solar collectors. In general, it is installed on the roof of buildings. The design of an active solar heating system must take into account the low density of solar energy reaching the earth's surface. Thus, the energy consumption of a single residence may require the installation of many square meters of flat solar collectors. A typical residence with three or four dwellers might need about 4 m² of collecting area, depending on solar radiation and heating demand.

Brazil has an enormous potential for solar energy use: —virtually all Brazilian regions has more than 2,200 sunshine hours annually, which means a potential equivalent to 15 trillion MWh, corresponding to 50,000 times the current national consumption electricity.

Even so, the infrastructure for water heating in most Brazilian households is based on electric shower, a very low investment cost equipment but requiring high consumption of electricity over its lifespan, which requires significant capital investments in the power sector in addition to considerable environmental and social burdens. Electric showers and boilers demand 8% of all electricity produced in Brazil and causes 18% of the peak demand in the electrical system.

According to Eletrobras, in 1989, energy consumption for water heating reached the second place in the end-use electricity segment in the residential sector representing a major problem for the Brazilian energy sector and at the same time, a huge potential investment opportunity for water heating.

Nevertheless, solar thermal technology cannot compete with electric showers regarding hot water supply: in 2002, the installed area per capita of solar collectors in Brazil was 1.2 m²/100 inhabitants, considerably less than that installed in Israel: 67.1 m²/100 inhabitants; Austria with 17.5 m ²/100 inhabitants and China with 3.2 m²/100 inhabitants.

To achieve the average installed area of solar collectors in countries affiliated to the International Energy Agency (IEA), the installed area in Brazil, which today is little more than two million square meters, should reach 7 million m². To achieve scores reached by Israel and Greece, countries that make intensive use this technology, the potential market would be between 35 and 167 million m² of collectors.

In this context, solar heaters correspond to a reasonable alternative for residential, commercial or industrial hot water supply, contributing to environmental and social impacts mitigation of the Brazilian energy sector.

Recently the Brazilian legislation compelled builders of residences for low incoming population to deliver them with solar heaters and also, several states, due to higher industrial power demands arising from the economic growth, have stimulated the use of solar energy by all citizens, industrial or commercial activities where they could be applied.

The major advantages for solar thermal energy using are:

-   -   1. Fossil fuels and hydroelectricity use replacement,     -   2. Emissions and local environmental burdens associated with         conventional energy sources reducing,     -   3. Low emission of gases and particulate materials that         contribute to urban pollution,     -   4. No additional flooding area required for electricity         generation,     -   5. No radioactive waste generation avoiding a dangerous legacy         for future generations,     -   6. Replacing fossil fuels, solar heaters reduce environmental         pollution consisted by nitrogen oxides, carbon monoxide, sulfur         dioxide, volatile organic compounds and particulate matter         preventing urban air pollution.

State of the Art advances brought by the “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, subject of this patent.

The “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, subject of this patent, represents a radical paradigm shift, both in the manufacturing process—whose steps were minimized due to automation—design and shape of the tubes for collecting solar energy ensuring tightness of the metal box which encloses the collecting part.

The phenomena concerning solar heating certainly arise in the consciousness of man at the same time that fire, i.e., in the beginnings of culture in its birth as mankind.

For the rising man, unequivocally, strand or high elevations black rocks could prove to be intolerably hotter than white ones in the sunniest hours of the day; they only warmed on sunny days failing to do this in evenings or during rainy periods.

For the mankind, the assumption that the sun had the power to warm bodies may have been preceded only by the perception of the effects of gravity on their bodies and objects.

All the advances brought by the State of Art of this patent can be simply demonstrated by:

-   -   1—the basic equations of Thermodynamics,     -   2—the innovative features afforded by the new geometric design,     -   3—the list of benefits from the innovative automatic collectors         manufacturing technique.     -   A—Thermodynamics considerations.

The basic equation applied to the object of the invention is Q=k.m.c.ΔT.A where “Q” is the amount of heat transferred per time, “k” is the coefficient of conductive heat transfer through the conductive interface, “m” is the mass subject to temperature changes, “c” is the specific heat of the substance subject to temperature changes, “ΔT” is the temperature change and “A” is the area exposed to heat exchanges.

This equation is useful to compute the heat exchanged between two fluids which flow in opposite directions separated by a metallic interface.

Although solar thermal collectors are not strictly heat exchangers, the principles of this equation are applicable to them.

In fact, in solar collectors, heat exchanges that taking place between two fluids separated by a metal interface represent only a small percentage of the energy involved and only occur between collecting tubes and heated gases that are trapped inside an insulator housing, which serves to insulate such tubes from ambient ventilation, preventing contact between these collecting tubes and the cooler surrounding air, and protecting its physical structure.

In solar collectors, electromagnetic waves which consist of the visible sunlight containing frequencies between 180 nm and 800 nm and also infrared radiation from sunlight, air and surroundings, longer than 800 nm wavelengths reach the external blackened walls of the collecting tubes and are then absorbed and transformed into heat, which crosses the interface consisting of the collecting tubes, and heats the water inside them which, by decreasing density, rises to the tank placed in a higher level promoting cold water circulation inside the collector from the cold water tank of towards the hot water tank, without any energy consuming except the inevitable heated water density decrease effect. It is evident that the power of such a machine:

-   -   a. is directly proportional to the available surface area for         absorption of radiation, whose solar energy gathering efficiency         increases as the surface radiation absortance increases;     -   b. is directly proportional to the material thermal         conductivity, whose sunlight gathering surface is made,     -   c. also results from the ability to prevent heat losses through         insulation of the heated parts aimed to collect solar energy and         to store heat in the tubes where water circulates.

The solar collector tubes, subject of this patent, are manufactured with the most efficient thermal conductor material of nature—copper—and by a new solar energy gathering tubes shape design, the surface/volume ratio of such tubes increases, increasing thus the efficiency of solar gathering surface.

Moreover, as in practice, the insulation of all hot surfaces composing the collector set also determines thermal machine efficiency, its solar radiation gathering tubes as well as its hot water tubes and also its storage are prevented from being cooled by contact with surrounding cold air, which can increase by the effect of wind, because they are insulated inside a watertight housing and the hot water tank is coated with thermal insulating material.

From the introduced equation, the phenomena of gathering energy from sunlight, its transformation into heat and energy transmission by contact with the water through the walls of the gathering tubes, we realized immediately that to collect a certain amount of heat per time under an effective sunshine conditions, the coefficient “k”, or any other directly related factor shown in the basic equation of Thermodynamics, being low return low system efficiency. The way to compensate such efficiency losses would be the area “A” increase, i.e. an overall cost increase, which is beyond the proposed subject of this patent, which aims “energy efficiency” and “low cost” in its manufacturing.

Therefore the author of this patent has developed creative ways not only to prevent the absorption area increase at the expense of increased size, weight and cost of materials and manufacturing of solar collectors, subject of this patent, but also to reduce these costs, as reported as follows.

-   -   B—The innovative features of the project geometric design and         the benefits from the innovative automatic collectors         manufacturing technique.

Initially, to obtain material savings, the use of aluminum tubes was abandoned, which are very cheap. However, in the short term, aluminum degrades due to chemical aggression of the compounds present in the water to be heated, causing serious damages.

The solar gathering tubes, subject of this patent, are manufactured of copper and have reduced costs—regarding manufacturing material, shape and manufacturing process—because of three innovative embodiments:

-   -   1. thickness reduction of the copper plates to 0.10-0.15         millimeters, which reduces the materials cost and the total         weight of the assembly;     -   2. molding of the gathering tubes by stamping of these in thin         plates, which gives structural stability to the thin plates,         thereby compensating its brittleness due to lower thickness with         thereof increased resistance conferred by stamping;     -   3. precise automatic laser or electrical discharge welding and         reduced costs without the use of electrodes or manual processes         of the two symmetrically stamped plates, so getting through a         single automatic manufacturing operation a whole hermetically         sealed tubes system for water circulating and solar energy         gathering.

Such innovation represents the shift from the era of expensive, large and problematic handcrafted solar heaters to the new era of industrially manufactured solar collectors automatically ensuring “Swiss” quality together with “Chinese” prices.

-   -   4. Besides this radical costs reduction arising from the         industrial design outlined above, by changing the geometry of         solar collector tubes that tend to have low internal volumes and         elliptical, oval, or any non-circular shapes, whose largest         diameters are positioned facing the sun to receive most of the         solar radiation, the area of absorption of solar energy through         the collecting tubes is increased. Due to huge problems         represented by the individual welding of the solar collector         tubes at both ends, both the cold water inflow tube and the hot         water outflow tube, manufacturers have used their practice of         making solar energy collectors with a reduced number of tubes         with substantial dimensions.

With the solar collector tubes assembling using stamping thin copper plate—0.15 mm thick—unlike what happens in conventional solar collectors, the preferred shape of construction, the subject of this patent exemplified herein and defined to technical, marketing and logistics project, uses copper plates of 0.15 mm thickness and 2,000 mm long by 610 mm wide—the solar collector tubes have 61 elliptical shape whose diameter is 7 mm and 5 mm, that is, between 10 and 17 times larger than the number of tubes of conventional solar energy collectors.

This amount of solar collector tubes whose dimensions refer only to preferred constructive manner, and can be wide-ranging assorted, the same as the dimensions of the sheets used.

The direct effects of the solar energy gathering tubes area decreasing, associated with concomitant tubes amount multiplication are:

-   -   a. volume increase of contained water inside the solar gathering         tubes reaching 3.53 liters per square meter of collector area;     -   b. 27% of increase of the available solar energy gathering area;     -   c. The combination of these two factors, considering the         preferred assembling arrangement of each unit of the subject of         this patent—whose gathering area dimensions are directly related         to the employment of copper plates of 2,000 mm by 610 mm—each         1.22 square meter have 1.54 square meter of energy absorption         area, representing gains of 27%.

Furthermore, regarding the manufacturing process of the subject of this patent, the usual simple practice of black covering of the collector surface was discarded, which on the other hand become oxidized in order to form a matte black film compound, such as sulfides that, once protected from the weather by the fact that solar energy collectors tubes remaining inside the insulator case of air or wind, has extra-long holding features lasting for decades, has the ability to maintain the black color and the matte surface constitution, thus ensuring high efficiency of absorption of solar energy during the whole lifespan of the solar collector assembly.

The result of the above stated innovations is that only a single unit of collecting solar energy from an subject of this patent, with 1.22 square meter of exposed to sunlight area can replace three conventional units with similar areas, which drastically reduces the initial investments in gathering solar energy for the same amount of collected heat and same temperature of the heated water.

Considering the high quality of the solar collector produced industrially by stamping process, automatic welding, and advanced capabilities to reduce costs and increase efficiency, combined with its long lifespan, one can estimate the price drop for the final consumer and the financial support to increase the practice to replace fossil fuels and hydropower for heating water for domestic and general purposes, with all worthy economic, social and environmental consequences of this practice.

Of course, as will be explained further, both the construction of airtight protective case against air infiltration and wind tightness of the tube connectors and a collector with external pipes for cool water supplying and hot water gathering are innovative and are also subject of this patent. They have long lifespan and have reduced maintenance costs, minimum 5 years supplier warranty can be provided, reaching eventually 10 year warranty.

To endorse our claim that industrial and automatic manufacturing of solar thermal collectors subject of this patent, from the manufacturing of multi-tube collector element through stamping and automatic welding, downgrades conventional techniques of solar collectors manufacturing based on handcrafting to the historical record. Let's inform that the total domestic production of solar collectors increased from 50,000 square meters in 1985 to about 1,000,000 square meters in 2010 in Brazil.

These are therefore core novelties brought by the State of the Art subject of this patent: —revolutionary industrial automatic manufacturing process after intelligent design, high thermal efficiency materials, advanced designs of components, hermetic sealing, and low cost and high reliability by automatic manufacturing.

Description, graphics and functioning of the “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, subject of this patent. Firstly, conventional solar collectors design will be illustrated and the problems derived from their technological design that rules their manufacturing are discussed; moreover the “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS” subject of this patent will be introduced regarding its essential details.

FIG. 1 reveals a frontal, schematic, and partial exploded view of a conventional solar collector showing a view to explain serious problems reflecting advances brought by the subject of this patent in comparison with earlier technics; thus, the conventional solar collector (1), in some way, the heated water outflow collector tube and cold water inflow collector tube (2), with their orifices (3), in which will be welded the solar energy collecting tubes (4), which, as explained before, are manually welded together one by one with the orifices (3), both (not shown) heated water outflow collector tube and cold water inflow collector tube (2).

As required, for cost reasons, the use of low thicknesses tubes of copper, the places for oxy-acetylene or electric arc welding, both welding modes also using wires or electrodes, even performed by welding experts, causes many weak points, both from the mechanical and electrochemical molding point of view, creating then points where corrosion shortly starts leading to, in short term, to discrete water drips and, in medium term, to the factual leakage associated with water and heat losses.

It is noteworthy to mention that the welding process is apropos a slow process and requires qualified and costly manpower increasing the final product costs due to its handcrafted concept. This paradigm cannot be avoided by current technique.

FIG. 2 shows a schematic superior view of the insulating housing (5), which houses the heated water outflow collector tube and cold water inflow collector tube (2), and solar energy collecting tubes (4), and whose upper face contains the covering glass (8), which, due to its chemical constitution, is permeable to the visible electromagnetic radiation and impermeable to low frequency electromagnetic radiation such as infrared waves, and preventing heat losses to the surrounding air, these losses are greatly increased by rain or wind incidences, a moment when heat gathering from solar light is most advantageous to the user.

We also see in FIG. 2 the classic assembly feature of the insulating housing (5) and the frame for the covering glass (8) consisting of a 45° cut (7) profiles of aluminum (6) which are subsequently folded to form the frame of a box with right angles, being filled with plastic adhesives, usually silicone, the gaps at the union of each 45° cut (7) with its corresponding part.

FIG. 3 presents a schematic frontal view of the insulating housing (5) showing the covering glass (8) and the forming of 45° cuts (7) of the aluminum profiles (6) housing it, as well as sidewalls (5A) of the insulating housing (5) with its orthogonal folds (5B), which hold the bottom plate (12), a set of parts assembled together through rivets or screws (11) and plastic adhesives, usually silicone, applied in the contact areas between these parts in order to produce the sealing of the insulating housing (5).

In the FIG. 3 we also see the solar energy collector element (9), composed by the heated water outflow collector tube and cold water inflow collector tube (2) and solar collecting tubes (4) and the thermal insulating plate (10), or generally built in polyols or expanded polyurethane resin, such as used in mattresses. Although such water tightness cannot be absolutely ensured by this assembling, since it is susceptible to imperfections from transportation and assembling operations, which by even minor accidents allow water infiltration into the insulating housing (5) even in small fractions, poor ventilation promotes then water accumulation in the bottom of the box and can be absorbed by the thermal insulating material (10), which work as a good thermal conductor, leading the gathered heat under the bottom of the of collector (9) to be dissipated to the environment by its bottom (12).

This situation, in case of small water leaks into the insulating housing (5), either from water coming from any of its internal parts or from rain that penetrated for any gap greatly decreases the equipment efficiency and subject to difficult and expensive maintenance processes.

FIG. 4 shows a schematic frontal view of the solar energy collecting element (9) shown in FIG. 3, so as to highlight the solar collector tubes (4) and to show the increase of the absorption of sunlight (13) by the plate, it is usually built in aluminum black painted flat plate, whose aim is to expand the area to solar energy collecting and to make contact between both heated metals: —aluminum for the plate and copper for the solar energy gathering tubes (4), which, as stated earlier, are few in number due to costs, weight and welding costs.

Thus, regarding labor and material costs, and low productivity presented by traditional solar collectors manufacturing methods, the so manufactured solar collector has low solar energy collecting efficiency, is subject to many imperfections, and has high maintenance costs compelling domestic consumers to acquire 2 or 3 units to ensure their domestic heated water supply. However, with the increasing Brazilian urbanization, apartments are the common building pattern. In this way, only penthouse apartments can take advantage of direct solar energy using 4-8 square meters for solar collecting. These traditional collectors are however inefficient. Owning the broadening of this benefit to other residents, the whole penthouse apartment exposed area has to be whole required, which will not occur if the subject of this patent which, given their reduced external dimensions allows them to be installed sufficient for all residents of smaller apartment buildings collectors.

FIG. 4 depicts the solution present by the traditional solar collectors dealers regarding its arrangement to increase solar energy gathering; there and in the references to elements in the previous figures, we see the solar gathering tubes (4) and solar energy gathering plate (13) with its specific shape to completely cover, above and below, or only partially, and partially and over, the mentioned solar energy gathering tubes (4), painted with matt black paint to increase solar energy gathering.

The “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, subject of this patent, with its innovative technology based on stamped and welded plates eliminates the solar energy solar energy gathering plate (13), saving material, labor and creating no points subject to corrosion. Notwithstanding the protection to all solar collecting tubes (4) and solar energy gathering plate (13) within the insulating housing (5), the almost inevitable presence of water between the two parts, which occurs along the time, allows the their contact with a water film and then, the set behaves like a voltaic pile leading to corrosion and to destruction of the electropositive metal.

FIGS. 5 and 5A shows the superior views schematically, illustrating the construction procedure though stamping and welding, which are both essential innovation subject of this patent, which can only be obtained by this means, as explained forward.

We see in the FIGS. 5 and 5A, as the shapes of each of the two sheets (C) and (C1) which, after being stamped identically and economically by the same stamping die and welded together as one (as further described below), will form the multi-tube stamped and welded collecting plate (14)—as shown its superior view in FIG. 5B.

The basic innovative principles of the product, as a result of its manufacturing Process—consisting of the innovative core subject of this patent—both are described below.

For intelligibility reasons regarding the illustrations, just two elliptical solar energy gathering tubes (15) are shown in the FIGS. 5, 5A and 5B, because are multiple—about 61 units—each unit having 610 mm width, subject of this patent, for the same reason, the proportions of the elements will neither be in compliance between them nor the technical requirements for metal stamping be shown, such as the curvilinearity considering the confluence of the elements.

FIGS. 5A and 5B depict, respectively, plates (C) and (C1) on which the elliptical solar energy gathering tubes (15) which follows at both endings comprising the cold water inflow tube (16) and the hot water outflow tube (17); after the plate welding (C) on the sheet (C1) a collecting and stamped welded multitubular plate (14) is composed, FIG. 5B shows its superior view, both endings of the cold water inflow tube (16) and the hot water outflow tube (17), further in a subsequent procedure, the connectors (18) are welded together, in compliance with the “NPT—National Pipe Thread Taper”, which is a special type of connector used for sealing threads that work subject to high pressures.

Plates (C) and (C1) shown in FIGS. 5 and 5A respectively are stamped by the same dip—constituted by punches and matrixes—whose production takes into account both symmetry, when superposed, so that when the plate (C1) is rotated 180° and placed on the plate (C)—or vice versa—the symmetry takes place, molding a volume, that is, creating between them, the stamped regions corresponding to tubes that they have the aim to develop after being stamped and superposed in 180° rotation, and also so that there is perfect match in the not deformed regions of the mentioned plates that then overlap with millimeter accuracy the regions aimed for welding process between both plates, which can be executed by the welding process “TIG—Tungsten Inert Gas”, laser or other suitable process, with automatically soldering features of copper surfaces with such small thicknesses.

As explained before and illustrated in the FIGS. 5, 5A and 5B, and also taking into account—as described on page 12/14—a stamped and welded multitubular collecting plate (14) is 610 mm wide and has 61 elliptical solar energy gathering tubes (15), whose outer diameters are 5 and 7 mm, with the largest diameters horizontally positioned, it is seen that the spaces are so small for inter-tubes welding and too large the amount of elliptical solar energy gathering tubes (15), that a so innovative and sophisticated stamped and welded multitubular collecting plate (14), as the subject of this patent, could only be done by a mechanized and high precision process and never by hand, promoting thus the evolution of a product—the conventional solar collecting plate made by a few tubes and manually welded—for the stamped and welded multitubular collecting plate (14), as a result, only possible by an innovative manufacturing process.

The set of elements shown in FIG. 5B: —the stamped and welded multitubular collecting plate (14), elliptical solar energy gathering tubes (15), the cold water inflow tube (16), hot water outflow tube (17) and connectors (18) are basically referred to as “solar collector”.

FIG. 6 shows a schematic superior view exhibiting the stamped watertight housing (20) containing in its interior the stamped and welded multitubular collecting plate (14) which, through connectors (18), in standard NPT, that you are welded and to which the flanges (19) are connected and bonded to stamped watertight housing (20) by use of industrial adhesives, and these flanges (19) which can be male or female terminals, represent the connecting elements of subject of this patent with the external tubes of the heating system—composed of ducts connected to the hot water tank and the cold water tank—not shown in this report.

FIG. 7 shows a superior schematic view of the stamped watertight housing (20), to show their covering glass sheet (21), which together with the connectors (18) and flanges (19)—shown in FIG. 6—is a set of devices that hermetically seals preventing atmospheric air contact—undisturbed or in the form of winds—with the stamped and welded multitubular collecting plate (14), this also hermetically sealed so that the main defects of the conventional solar collectors, e.g. water leaks and their negative consequences on the whole equipment efficiency, avoiding gathered solar heat loses and corrosion, are radically reduced.

In the FIG. 7 we see that, unlike the insulating housing (5) of conventional solar collectors, shown in FIG. 2, the stamped watertight housing (20), for being stamped and have its covering glass (21) cemented with durable adhesives (23) on a broad base (22) of the stamped watertight housing (20), to encloses the covering glass (21) has no openings for moisture and rain infiltration.

FIG. 8 represents a frontal schematic view of the stamped watertight housing (20) showing the tightness provided to the contact area between it and the covering glass (21) through its wide base (22) which is filled with adhesives (23) suitable for sealing required. We also see in the FIG. 8 the stamped and welded multitubular collecting plate (14) and thermal insulation (24) which can be polymer, glass wool, expanded vermiculite or any other material and able to thermally insulate the stamped and welded multitubular collecting plate (14) and the heated fluids inside the stamped watertight housing (20), exhibiting low cost, efficiency and long lifespan.

The stamped watertight housing (20), can be made from any material, but preferably in matte black anodized aluminum.

FIG. 9 shows a schematic frontal view of the elliptical solar energy gathering tubes (15) aiming to show how is the light absorption as function of elliptical, oval or non-circular geometric shapes, since properly positioned they provide larger sunlight absorption area along the time of sunshine, when compared to a circular shape, which also happens with the moon, with a maximum area of illumination occurs by means of its hemispherical shaped cap, as shown in FIG. 9, the horizon H line, the T line embodying the Sun (S) apparent path and the area (A1), (A2), (A3), (A4) and (A5) of sunshine incidence on a unit of elliptical solar energy gathering tubes (15).

Thus, thanks to the innovative elliptical, oval or any other shape of closed non- circular curved solar energy gathering tubes, which increases the area of solar energy collecting, and thanks to increasing of the area of solar energy capture by increasing the number of collecting tubes around 10 to 17 times of the number of circular shaped tubes from conventional solar collectors, and thanks to stamped watertight and seamless housing and also through a revolutionary mechanized and low cost manufacturing process regarding stamping and automatic welding, the “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, subject of this patent, exhibiting lower consumer price, long lifespan and with an apparent solar collecting area of only 1.22 square meters, can replace about 3 or 4 units of conventional solar collectors. 

1. “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, which uses copper plates with small thickness, has its collecting tubes formed by stamping and are joined by automatic welding process, by laser or electrical discharge of high precision and with increased solar energy gathering area by increasing the number of collection tubes at about 10 to 17 times more than the number of tubes of circular shape of conventional collectors, introducing solar collecting tubes with reduced internal volumes and elliptical, oval, or any non-circular shapes, whose largest diameter are positioned facing the sun and still more 0.10 to 0.15 mm thick copper plates for stamping process and making use of symmetric stamped plates (C) and (C1) that welded together, constitute the stamped and welded multitubular collecting plate (14) which has approximately 61 elliptical solar energy gathering tubes (15) for each 610 mm wide unit, namely (C) and (C1) plates assembled so as to create between them and the stamped spaces corresponding to the mentioned elliptical solar energy gathering tubes (15) and so that there is complete match in the non-deformed regions of the mentioned plates that turn into to accurately overlap together and which are the regions where the welding between the two plates take place, which can be executed by the “TIG—Tungsten Inert Gas” process, laser, or any other suitable process, with features capable for automatic welding between copper surfaces with reduced thickness and also by the fact that the stamped and welded multitubular collecting plate (14), elliptical solar energy gathering tubes (15), cold water inflow tube (16), hot water outflow tube (17) and connectors (18) constituting the flat solar collector.
 2. “FLAT TERMO-SOLAR COLLECTOR AND MANUFACTURING PROCESS”, according to claim 1, a device characterized by the stamped watertight housing (20), having in its interior the stamped and welded multitubular collecting plate (14) which, through connectors (18) in accordance with NPT standard are you assembled by welding and to which the flanges (19) are assembled and bonded with industrial adhesives together with the walls of the stamped watertight housing (20), and these flanges (19), which can be male or female terminals, are the connecting elements of the flat solar collector with external tubes of the heating system—composed of tubes connected to the hot water tank and the cold water tank and also the thermal insulator (24) on its bottom.
 3. “FLAT SOLAR COLLECTOR TERM PLAN”, according to claim 3, a device characterized by the stamped watertight housing (20) composed by the covering glass (21), which together with the connectors (18) and flanges (19) represents a set of devices which hermetically prevent the contact between the surrounding atmospheric air and the with stamped and welded multitubular collecting plate (14). 